Journal of Insect Physiology

Iron is an essential nutrient for all types of organisms, including insects and the microbes that infect them. We predicted that insects fed an iron-supplemented diet would accumulate more iron in their hemolymph, and, because infectious microbes acquire iron from their hosts, that this extra iron would increase the severity of bacterial infections. To test this hypothesis, we studied the effects of dietary iron supplementation on infection outcomes in Manduca sexta (tobacco hornworm). Larvae were fed an artificial diet, with or without antibiotics, or the same diets supplemented with 10 mM iron. Control and iron-treated larvae were inoculated with non-pathogenic Escherichia coli or the entomopathogenic Enterococcus faecalis, and bacterial load and larval survival were measured. We found that dietary iron supplementation increased the iron content of hemolymph by approximately 20 fold; however, contrary to our prediction, this increase in iron did not result in an increase in the bacterial load of either E. coli or E. faecalis. The effect of iron supplementation on survival was more complicated. As expected, for larvae inoculated with nonpathogenic E. coli, iron supplementation had no effect. For larvae inoculated with E. faecalis, the effect of iron supplementation depended on whether antibiotics were present in the diet. Without antibiotics, iron supplementation prolonged larval survival; with antibiotics, iron supplementation decreased larval survival. The results of this study do not support the hypothesis that dietary iron supplementation increases infection severity in M. sexta. Instead, the results support the viewpoint that the relationship between dietary iron and infection outcome is complex.

O_LIChill-susceptible insects such as Drosophila are vulnerable to progressive disruption of ion and water homeostasis during cold stress, and low temperature exposure is a key factor affecting their physiology and distribution. Comparative studies of cold tolerance traditionally use simple or single-condition assays for interspecific comparisons, but the emergence of thermal death time (TDT) models offers a comprehensive framework to assess cold tolerance across different stress intensities and durations. C_LIO_LIHere we construct TDT curves for six Drosophila species, spanning boreal to tropical habitats, using Lt50 estimates across a range of stressful low temperatures (Lt50 ranging from [~] 20 min to 2 days). For all species, the TDT curves provided good fits to the log(Lt50) vs. temperature data (R2 = 0.87 - 0.99). C_LIO_LITDT curves from all species had steep slopes demonstrating that cold injury rate has a high thermal sensitivity such that small changes in temperature have profound effects on survival duration. The interspecific similarity of TDT slopes indicates that a conserved physiological dysfunction underlies cold injury across species. Further, additive accumulation of cold-induced injury in split-dose experiments suggests that acute and moderate cold damage represent the same underlying physiological dysfunction occurring at different rates. C_LIO_LIThe TDT curve intercepts (species-specific tolerance thresholds) differed markedly between boreal, temperate, and tropical species and correlated strongly with their habitat temperature. Data from the present study and meta-analysis of published data find that the inherent species cold tolerance decreases by [~] 0.45 {degrees}C for each {degrees}C colder the winter environment of the species is. When also considering the cold acclimation cues in cold climates we argue the experienced level of cold stress intensity is similar across environments inhabited by the Drosophila genus. This suggests that cold tolerance is important in shaping the fundamental niche of both boreal and tropical species. C_LIO_LIOverall, the TDT analysis of Drosophila at low temperature provides a powerful and predictive tool for quantifying insect cold tolerance. This approach enables detailed cross-species comparisons that allows for both ecological and physiological inference. Thus, TDT curves offer relevant approximations of insect cold resistance that could help predict insect responses to climatic change. C_LI

Kissing bugs are the primary vectors of Trypanosoma cruzi, the causative agent of Chagas disease. Kissing bugs are exposed to thermal variability, including short periods of heat stress, which can induce mortality or exert sublethal effects. This study investigated Rhodnius prolixus following brief periods of high thermal stress with respect to survival, blood feeding, developmental processes, and T. cruzi infection, with a focus on sublethal effects. Our results demonstrated a significant decrease in survival for R. prolixus at 42 {degrees}C for 8 hours. When exposed to sub-lethal thermal stress (40{degrees}C for 8 hours), blood ingestion (amount and proportion) was reduced after 24 hours of recovery from thermal stress. Among the bugs that fed after 24 hours, molting was not impacted by temperature exposure. The infection rate decreased after heat exposure, likely due to reduced blood volume ingested when feeding 24 hours after heat stress. A week of recovery after exposure to higher temperatures improved feeding and increased infection rates to levels comparable to those of kissing bugs not exposed to thermal stress. Our findings offer insights into how extreme temperature events may influence Chagas disease. Specifically, these studies highlight the need to clarify how temperature, particularly at sublethal levels, interacts with vector biology to alter parasite transmission.

Black soldier fly larvae (BSFL) have quickly become one of the most farmed animals in the world. However, little is known about how to monitor stress and welfare in these animals. The difficulty of welfare assessment is compounded by the fact that BSFL live in their feed and prefer darkness. This behaviour makes it challenging to observe potential welfare indicators without inducing stress via disturbing the larvae or moving them into the light. However, acoustic devices may be able to pick up signatures of stress in the population even while they are out of sight, allowing for remote monitoring of animals in natural conditions (in the feed and/or in the dark). Acoustic monitoring of this type has been deployed for the detection of insects in stored grains, suggesting this method holds some promise for assessing insect behavioural signatures. In this study, we aimed to identify general, acoustic signatures of stress in BSFL by recording them during exposure to two stressors (light or shaking) or in a low-stress control condition. Our data suggest there are consistent differences in the acoustic recordings of the non-stressed and stressed conditions that may indicate the animals behaviours shift consistently in response to stress. Ultimately, the data suggest acoustic monitoring may hold promise for larval behaviour and/or welfare assessment and should be further explored in response to a variety of stressors across the larval life stage.

The greater wax moth, Galleria mellonella, is an increasingly important invertebrate model for infection biology, yet silk extrusion during handling complicates larval injections and hampers survival assessment. Here, we develop and characterise a simple cold-shock method that reliably inhibits silk production without compromising larval viability. Larvae exposed to -20 {degrees}C for 10 minutes completely suppress silk extrusion with 100% survival, representing a substantial improvement over previous chilling approaches. Cold-shocked larvae successfully remained capable of completing development, although pupation and adult emergence were delayed, body weight and fecundity were reduced, and wing deformities were more common. While cold-shock did not alter silk gland morphology, spinneret structure, or fibroin gene expression, confocal imaging revealed pronounced disorganisation of F-actin and -tubulin networks within silk gland cells, indicating cytoskeletal disruption as a likely mechanism underlying silk inhibition. When challenged with Escherichia coli, cold-shocked larvae responded comparably to controls, with survival influenced primarily by feeding status. Together, these findings demonstrate that short-term cold-shock provides an efficient, reproducible, and easy implemented method for preventing silk extrusion in Galleria larvae, markedly improving handling and experimental safety while preserving their suitability as a model host for pathogen research. HighlightsO_LICold-shock at -20 {degrees}C for 10 minutes inhibits silk extrusion. C_LIO_LILarvae survive treatment with no loss of suitability for infection studies. C_LIO_LIDevelopment slows and adult weight, fecundity, and wing quality decline. C_LIO_LISilk glands stay intact; gene expression remains unchanged after cold-shock. Cytoskeletal disruption likely drives the failure of silk secretion. C_LI

O_LIEctotherms in thermally variable environments mediate energy expenditure through both physiological and behavioural responses. However, many studies focus on constant temperature acclimation, and few consider behaviour and physiology in unison. It is unclear how acclimation to thermal variability affects locomotory choices, activity timing, and performance across daily thermal cycles. C_LIO_LIWe investigated the effects of thermal variability in the temperate dung beetle Onthophagus taurus. Following acclimation to a low amplitude (22{degrees}C {+/-} 2{degrees}C) or a high amplitude (22{degrees}C {+/-} 10{degrees}C) temperature regime, we measured behaviour and metabolic rate across temperatures. We hypothesised that O. taurus adjusts its locomotive strategy and search window when kept in high amplitude fluctuating temperatures to reduce energy loss associated with high temperature exposure. C_LIO_LIWe found that differences in energy expenditure were determined by propensity for flight which differed between acclimation treatments, particularly at intermediate temperatures. We also found that, following acclimation to a high amplitude of thermal variability, O. taurus exhibited a greater intensity of activity over a narrower window of time, and O. taurus acclimated to a low amplitude of thermal variability showed nocturnal activity. C_LIO_LIWe then used the data to model activity through the growing season over five years. Biophysical models were built using NicheMapR Microclimate and Ectotherm functions to test the length of potential searching time across seasons, the temperatures individuals are exposed, and locomotive strategy. Model outputs showed that acclimation to higher amplitudes of thermal variability increased accumulated degree-hours of activity relative to the low variability acclimation group. Individuals acclimated to higher amplitudes of thermal variability showed greater accumulated degree-hours in spring and fall, but exhibited shorter periods of activity during summer, with the model predicting increased opportunities for flight. Comparatively, O. taurus from the low variability acclimation treatment showed increased night activity in summer but did not fly. C_LI

This protocol generates gregarious and solitarious density-dependent phenotypes in multiple Schistocerca species under controlled environmental conditions. It describes cage setup, feeding, animal handling, and sterile dissection workflows to isolate nervous, chemosensory, gut, fat body, and female reproductive tissues from nymphs and adults. It emphasizes rapid tissue stabilization and RNase-control practices for downstream single-tissue DNA and RNA analyses. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=136 SRC="FIGDIR/small/705994v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@119ec2forg.highwire.dtl.DTLVardef@e115b7org.highwire.dtl.DTLVardef@158ad1dorg.highwire.dtl.DTLVardef@cd54d7_HPS_FORMAT_FIGEXP M_FIG C_FIG

Nocturnal migration is a remarkable phenomenon observed in many insect species, including moths. Migratory moths are capable of maintaining precise directional orientation during migration, as demonstrated in both laboratory and field studies, suggesting that they use multiple environmental cues for orientation and navigation. Recent studies on Australian Bogong moths revealed that these animals can use stellar cues and likely the geomagnetic field (in conjunction with local visual cues) to select and maintain population-specific migratory direction. However, the underlying orientation mechanisms used by most other migratory moths are still largely unresolved. Further, it remains unclear whether migratory moths can adjust their orientation using Earths magnetic field parameters for determining their position relative to the goal (i.e. location or map information) - an ability clearly shown in some migratory birds which respond to virtual magnetic displacements by correcting their orientation (experiments when animals are exposed to magnetic cues corresponding to other geographic locations). Here, we present results from virtual magnetic displacement experiments conducted on red underwings (Catocala nupta). In addition, we tested their orientation under simulated overcast conditions and in a vertical magnetic field to get indications whether this species relies on geomagnetic or celestial cues to maintain its population-specific migratory direction. Our results show that (1) red underwings did not compensate for virtual magnetic displacement, indicating the absence of a magnetic map; (2) they remained significantly oriented in the absence of geomagnetic information, suggesting the use of a stellar compass; and (3) there was no evidence of magnetic compass orientation in absence of any visual cues.

Animals sense and integrate complex external cues to make developmental decisions that help them better survive and adapt to their natural habitats. Under environmental adversity, nematodes can enter an alternative developmental pathway to form a diapautic and stress-resistant stage, termed the dauer larvae. While dauer formation has been well characterized in Caenorhabditis elegans, how environmental factors influence analogous stages in other nematode species remains largely unexplored. This study examines how symbiotic bacteria, temperature, and pheromones affect the formation of the infective juvenile (IJ), a dauer-like stage, of the insect-parasitic nematode Steinernema hermaphroditum. In contrast to C. elegans, where dauer entry is promoted by heat, IJ development in S. hermaphroditum development is enhanced by reduced temperature. Moreover, the presence and absence of live symbiotic bacterium Xenorhabdus griffiniae functions as an ON-and-OFF switch that regulates the host IJ formation. Crude pheromone extracts from S. hermaphroditum liquid culture do not robustly induce IJ formation in a dose-responsive manner, unlike the potent pheromone-driven dauer entry observed in C. elegans. Nutrient-rich liver-kidney media that mimics host insect environment showed IJ entry induction in a pheromone-dependent manner. These data suggest that external cues, such as temperature, microbial diet, and pheromone, are perceived differently by S. hermaphroditum in comparison to that of C. elegans, reflecting species-specific adaptations to distinct ecological niches and life history strategies.

We examined how thermal shifts influence development time and adult body size in Drosophila melanogaster. Individual flies were exposed to alternating temperatures of 25{degrees}C (optimal) and 17{degrees}C (cold), with shifts introduced at key developmental transitions: larval hatching and pupariation. We found while larval-stage temperature is the biggest determinant of thermal plasticity of development time and adult size, the egg-stage temperature also influences the pace of development and growth throughout pre-adult duration. The effect of low-to-high and high-to-low temperature shifts on development and growth may not be symmetric. When eggs are reared at 25{degrees}C and then shifted to 17{degrees}C, larval and pupal durations undergo reduction compared to constant 17{degrees}C, but it produces slightly larger adults. A higher egg-stage temperature thus seem to exert a carryover effect that accelerates subsequent development and growth when later stages experience colder temperatures. Surprisingly, flies whose egg stage is exposed to 17{degrees}C followed by a shift to 25{degrees}C also have reduced larval duration and larger size, relative to those developing at constant 25{degrees}C. We speculate this could be either because 17{degrees}C to 25{degrees}C represents a low-to-high temperature shift or a sub-optimal-to-optimal thermal shift that results in metabolic and/or hormonal changes accelerating differentiation and growth. While pupal duration is sensitive to current and to some extent prior thermal environments, it does not contribute substantially to thermal plasticity of size. Development time is longer in males than in females, and this difference seems to start from larval stage while the pupal duration plays a bigger role in creating this sex-specific difference. Overall, employing individual fly rearing, this study helped to unravel the effect of thermal shifts on growth and development in D. melanogaster with great precision.

Local temperatures can shape the ability of introduced species to flourish and disrupt novel environments. The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an invasive beetle that threatens ash trees in North America and Europe. To assess the role of temperature on EAB reproduction, we reared groups of adult beetles at one of four temperatures (12, 15, 18, and 21 {degrees}C) and measured reproductive success (laying fertilized eggs and egg hatching). There was no effect of rearing temperature on EAB female lifespans but no eggs laid at 15 or 18 {degrees}C hatched, suggesting these temperatures disrupt the reproductive process of EAB. Females reared at 21 {degrees}C, however, consistently laid eggs that hatched. We then used these results to assess the likelihood of reproductive success over the previous ten years in eight cities in Canada that host EAB. All locations experienced temperatures of [≥] 21 {degrees}C, but the number of hours and the number of days above this critical temperature were highly variable. There were ample opportunities in all locations for EAB to reproduce, but EAB in cooler cities would experience thermal limitations thus slowing the spread of EAB populations.

Carausius morosus, the Indian stick insect, is a slender twig-like insect endemic to India. Though widely introduced through captivity around the world and commonly used in laboratories or kept as a household pet, standardized animal husbandry laboratory protocols are lacking. Here we report detailed laboratory culture conditions for C. morosus. We maintain stocks at 23 {degrees}C, 70% relative humidity, and a 12:12 hour light-dark photoperiod. This culture has been successfully sustained under these conditions for over two years, with standardized protocols in place for dietary and cage setup conditions. We also report methods for egg and hatchling care to support ongoing experiments with C. morosus. These standardized methods improve reproducibility and accessibility, enabling the broader use of C. morosus as a laboratory model system for developmental, behavioral, and physiological studies. SummaryThis paper outlines detailed protocols for maintaining a Carausius morosus laboratory colony, including key procedures for animal husbandry, egg and hatchling care, and an overview of the species lifespan and biological characteristics.

Understanding the nutritional preferences of honey bees (Apis mellifera) is essential for comprehending their behavioral ecology and the division of labor within a colony. While gustatory sensitivity to sucrose is well-documented in workers, a significant research gap exists regarding the sensory responses of queens and their reactions to caste-specific nutrition such as royal jelly. This study utilized the proboscis extension response (PER) assay to compare the food preferences of three distinct bee categories: foragers, 1-day-old workers, and queens. Subjects were presented repeatedly, in a pseudorandom order, with water, sucrose, royal jelly, and a sucrose-royal jelly mixture as gustatory stimuli. Foragers exhibited a high responsiveness to sucrose and showed uniformly low responsiveness to other stimuli. Although 1-day-old workers showed high responsiveness to sucrose, unlike foragers, they also responded to the sucrose-royal jelly mixture. Queens displayed a unique response profile, with near-ceiling responsiveness to both royal jelly and the mixture, followed by response to sucrose solution without habituation. Additionally, responsiveness to the sucrose was higher in foragers than in 1-day-old workers. These findings suggest that the honey bee gustatory and sensory system is tuned to the specific nutritional requirements of caste and age.

Animals need to precisely perceive and integrate the environmental cues to orient and select the appropriate motor responses required for navigating. This is the case, for instance, of the optokinetic reflex (OKR) and the optomotor response (OMR) in Drosophila melanogaster, where optic flow stimulation modulates the head or the body and legs motor activity respectively. Despite large bodies of literature on both the OKR and the OMR, there is still a limited understanding, in flies, of the impact on these responses of concomitant, and potentially conflicting, sensory inputs. To investigate this aspect, we used fruit flies walking on a sphere, presented with optic flow stimulation leading to the OMR together with the simultaneous exposure to olfactory stimulation, either using established repellent or masking compounds. We analysed the effect of different substances, and of their concentration, on the dynamics of the flies response to moving gratings, evaluating the fly walking path as well as average speed and duration. This analysis revealed several alterations between the compounds tested, in agreement with reported data on the simpler OKR. In conclusion, we show that concomitant exposure to repellents and maskers may consistently affect fundamental processes (the OKR and OMR) available to insects for informing themselves while navigating through the environment.

High annual honey bee colony losses are associated with environmental and biological stressors, including virus infections. In insects, the octopamine pathway orchestrates the "fight-or-flight" response, regulating energy mobilization, temperature, and flight. We determined that sacbrood virus (SBV) infections induce expression of an octopamine receptor and enhance honey flight performance, whereas deformed wing virus (DWV) infections reduce flight performance, but how viruses interface with this pathway remained unknown. To elucidate the relationships between the octopamine response, virus infection, and flight, honey bees were infected with SBV or DWV and exposed to octopamine (OA), epinastine (EP)-an OA receptor antagonist, or both OA and EP; flight and gene expression were assessed. Pharmacologic manipulation revealed that octopamine supplementation rescued flight deficits in DWV-infected bees, but diminished performance in SBV-infected bees, while blocking octopamine receptors altered these effects. Transcriptome analyses indicated that SBV infections, and DWV infection with OA treatment, activated honey bee metabolic pathways, and that SBV infected bees had greater expression of genes involved in OA synthesis, unless treated with OA. These results provide a mechanistic explanation for virus-specific impacts on honey bee flight, which may have consequences on foraging efficiency, colony health and virus transmission.

O_LIPhenological shifts are a major ecological consequence of climate change, yet studies often focus on single life stages meaning that the potential for carryover effects between life stages remains poorly understood. Failing to account for these effects may lead to inaccurate estimates of phenological shifts, with consequences for predicted synchrony among interacting species. This is especially relevant for temperate systems where climate warming is occurring unevenly across the year. C_LIO_LIHere, we investigated how temperature experienced the previous autumn and winter (during the pupal and egg stage) influences spring phenology in the winter moth (Operophtera brumata), a herbivorous insect with distinct life stages. Using 50 years of local climate data to create five experimental temperature regimes, we first quantified phenotypic plasticity in the duration and temporal variability of pupal and egg development. We then examined how timing of adult moth emergence affects timing of offspring hatching. C_LIO_LIWe found divergent effects of temperature on different life stages; pupal development time was shortest at intermediate temperatures while egg development time decreased linearly with increasing temperature. Furthermore, phenological shifts due to the conditions experienced by the mother were carried over to influence the phenology of her offspring. While this carryover effect was partially compensated during subsequent stages, compensation decreased under warming conditions. C_LIO_LIThese results refine our understanding of the sensitivity of the annual cycle of winter moth phenology to variation in temperature with potential implications for population dynamics and interspecific interactions. Overall, our findings highlight the need to consider the impacts of warming across multiple life stages so that carryover effects can be properly accounted for. Doing so will improve predictions of phenological shifts under future climates. C_LI

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=118 SRC="FIGDIR/small/700930v1_ufig1.gif" ALT="Figure 1"> View larger version (63K): org.highwire.dtl.DTLVardef@177a6b4org.highwire.dtl.DTLVardef@6186a3org.highwire.dtl.DTLVardef@ce6196org.highwire.dtl.DTLVardef@168bf43_HPS_FORMAT_FIGEXP M_FIG C_FIG The kangaroo soft tick, Australpavlovskyella gurneyi (Warburton, 1926), is found in sandy depressions ( wallows), under desert shade trees, formed by the activity of the red kangaroo, Osphranter rufus, resting under shade trees (https://youtu.be/AYLoqqPsifc). The field biology of the tick was examined on Moralana Station in arid mid-north, South Australia, between February 1969 and March 1971. The age of kangaroo dung in wallows showed that kangaroos visited wallows regularly during the hot summer and infrequently during the cooler months. All nymphal instars and adults were present at all times of the year in kangaroo wallows, but only a small proportion of the ticks present was trapped on any one occasion. Ticks were abundant in large kangaroo wallows under trees with dense shade, but scarce under smaller trees with sparse shade. The short-lived larvae were present only during spring and early summer, indicating that the long-lived female ticks bred only during spring and early summer. Laboratory tests showed that field-collected adult female ticks entered reproductive diapause from January to August (mid-summer to late-winter). Ticks placed in kangaroo wallows survived for at least one year without food. On Moralana Station, the population of first-instar nymphs increased in summer and subsequently the population of second-instar nymphs increased in early autumn, indicating that a life cycle could be completed in 2-3 years. HighlightsO_LIThe seasonal biology of Australpavlovskyella gurneyi, found in sandy depressions wallows formed by the activity of the red kangaroo, under sparse semi-arid desert shade trees was examined for the first time. C_LIO_LIEngorged ticks placed in kangaroo wallows survived for at least one year without food. C_LIO_LIIn this environment, the entire life cycle could be completed in 2-3 years. C_LI

Microbial residents of ectothermic hosts are exposed to variations in temperature that have the potential to impact their physiology and the host-microbe symbiotic relationship. In this experimental warming study, laboratory populations of American cockroaches (Periplaneta americana) were kept at a baseline low room temperature of 20-22{degrees}C or a high temperature of 30{degrees}C for two weeks. We quantified bacterial load and performed high-throughput 16S rRNA gene sequencing to assess the hindgut microbiomes response to a near 10{degrees}C shift in environmental temperature. We report modest impacts of temperature on cockroach gut microbiome composition. The high temperature treatment induced increases in the relative abundance of Proteobacteria and Euryarchaeota phyla as well as the Lactobacillaceae and Enterococcaceae families. We also observed increased interindividual variability. There were no significant differences in the dominant Bacteroidota or Firmicutes phyla and no significant losses or reductions in taxa or bacterial load, respectively. This suggests that the gut community of American cockroaches is largely resilient to prolonged increases in temperature and has implications for the cockroach to withstand the impacts of climate change. ImportanceInsects, as with most animals, often harbor microbial symbionts that play an essential role in host health and nutrition. As insects are ectotherms, these microbial symbionts are subject to the same temperature fluctuations as their hosts, potentially impacting host temperature responses. Here, we demonstrate that the American cockroach (Periplaneta americana) gut microbiome exhibits only modest changes following an [~]10{degrees}C increase in environmental temperature. This contrasts with studies in other insects, whose microbiota were highly responsive to temperature variation. This work illustrates that the microbiota of insects may vary in their sensitivity to long-term temperature shifts, providing a more comprehensive understanding of potential variability in insect responses to climate change.

Aedes aegypti mosquitoes transmit multiple arboviruses, but population suppression through the mass release of sterile or incompatible male mosquitoes can effectively reduce populations. These methods depend on the reliable mass-rearing of healthy, robust males that can successfully mate with wild females. The microbiota, a critical component of the larval diet, can dramatically influence life history traits relevant to mass-rearing and male quality. Here, we used axenic (microbe-free), monoxenic (inoculated with E. coli), and "laboratory community" mosquitoes (inoculated with an undefined microbiota derived from laboratory mosquitoes) to show that longevity was significantly enhanced in axenic and monoxenic males compared to laboratory community males. Moreover, monoxenic males more efficiently obtained mates in non-competitive mating scenarios compared to laboratory community males. However, microbiota treatment had no effect when males from different treatments competed for a mate. Our findings suggest that the microbiota is a key determinant of male mosquito life history with direct implications for optimizing production of males for control programs. TeaserThe microbiota of Aedes aegypti mosquitoes affects multiple male life history traits.

A major challenge to investigating the proximate causes of ecological adaptation is the difficulty of studying the phenotypes of organisms in their natural environments. By necessity, many studies seeking to determine the genetic and cellular basis of adaptation therefore investigate potentially adaptive phenotypes under laboratory conditions where organisms are more easily experimentally manipulated. For laboratory models, it remains unclear if organisms maintained long term under laboratory conditions are representative of relatives in their natural environment. In recent years, Drosophila sechellia, a specialist species endemic to the Seychelles, has emerged as a (neuro)genetic model for studying the molecular basis of ecological adaptation. A multitude of studies have investigated the genetic and cellular basis of various aspects of this species specialization in a laboratory setting. However, the vast majority of these studies use laboratory strains of D. sechellia that were collected many decades ago, and have been maintained under conditions very different from their natural niche. Thus, it remains unclear if and how these strains resemble their wild counterparts. Here, we compare the phenotypes of these laboratory strains with recently-collected wild D. sechellia to ask if laboratory strains display a loss or degradation of phenotypes potentially involved in their specialization resulting from their long-term laboratory maintenance. Across several behavioral and anatomical phenotypes, we find a high degree of similarity between wild-caught and laboratory-maintained strains. Our results suggest that studies of the molecular mechanisms underlying D. sechellias phenotypes associated with specialization are likely representative of the evolution of these flies in the wild.